GRINDING TEETH. 



327 



It is worthy of remark that, even at the present day, the 

 custom of grinding corn is carried out in Palestine as it was so 

 many centuries ago, and that it is repeated in Southern Africa 

 among the Kafir tribes. In both parts of the earth the first 

 sound of early morning is caused by the millstones of the 

 grinding women, and the amount and duration of the noise 

 afford a sure test of prosperity. Cessation of the millstones 

 signifies adversity and a thin population, as has been said by a 

 writer who lived not very far from three thousand years ago. 

 Speaking of tribulation, he mentions that " the grinders cease 

 because they be few, and that the doors shall be shut in the 

 streets when the sound of the grinding is low." 



After awhile improvements were gradually introduced into 

 the business of grinding, not the least of which was covering 

 its surface with ridges, instead of leaving it entirely smooth, as 

 it had been formerly. Millers of the present time know the 

 value of these ridges, and the additional grinding power which 

 this " facing " gives to a stone. One of these stones is repre- 

 sented in the illustration, so as to show the system on which 

 the ridges and grooves are constructed. 



Now, passing from Art to Nature, we find that the whole 

 system of the millstone, its movement and its ridged sur- 

 face, existed in the times when man had not yet come upon 

 earth. 



The reader is probably aware that among the tooth-bearing 

 animals there are three types of teeth. First come the incisors, 

 or cutting teeth, which occupy the front of the jaw, and find 

 their fullest development in the rodent animals, such as the 

 beaver, the squirrel, the rabbit, and the rat. Next them 

 come the canine or piercing teeth, which are so highly de- 

 veloped in all the cat tribe. Lastly, there are the molar or 

 masticating teeth, so called from a Latin word signifying a 

 millstone, because their office is to grind food. 



As it is with these last that we have now to treat, we will 

 say nothing about the others. 



The molar teeth find their greatest development in the 

 Elephant, the structure of whose molars is exactly like that of 

 our modern millstones. There is certainly one very great 

 difference. When the surface of a millstone is rubbed away, 



